Means for automatically controlling voltage and power factor of generators operating in multiple.



/ PATENTED MAY 12, was, J. PEARSON.

MEANS FOR AUTOMATICALLYCONTROLLING VOLTAGE AND POWER FAGIGP.

OP GENERATORS OPERATING IN MULTIPLE.

APPLICATION FILED MAR. l, 1906.

Winmses UNITED PATENT OFFICE.

JOHN PEARSON, O1 SOMERSET, WISGONSIN, ASSIGNOR OF ONE-THTRD TO JAMES F. WILLIAM SON AND ONE-SIXTH TO FRANK D. MERCHANT, 01* MINNEAPOLIS, MINNESOTA.

MEANS FDR AUTOMATTGALLY' GUNTROLLlING VOLTAGE AND POWER FACTOR CFfzrEN- ERATOBS OPERATING IN MULTIPLE.

Patented May 12, 1908,

Application filed March 1, 1906. Serial No. 303,639.

To all whom it may concern: r

Be it known that 1, JOHN PEARSON, a citizen of the United States, residing at Somerset, in the county of St. Croix and State of Wisconsirnhave invented certain new and useful Improvements in Means for Automatically lontrolling Voltage and Power Factors of Generators Operating in Multiple; and I do hereby declare the following to be a full, clear, and exact descri tion. of the inven tion, such as will enable olihers skilled in the art to which it appertains to make and use the same.

Thisinvention relates to the regulation of voltage and power factor in electric generatin and transmission systems, and has for its 0 ject to rovide means for automatically controlling t. e fields of generators located in I Tirrill voltage regulator,

distant stations, in such manner that it is ossible and racticable to operate the same in multiple w on delivering e ectrical energy over the same transmission line.

Es eciall' this invention relates to the inter epen out control of a plurality of vol- .tage regulators such as the General Electric with the said voltage regulatorsconnected to regulate the fields of generators in.

different generating plants, whether in close roximity or at considerable distances apart, liut particularly when the stations including such voltage regulators are far apart and where the percentage of drop in voltage of the one station varies greatly, with respect to that of the other station.

In the accompanying drawings, Figure 1 is a diagram showing. the invention applied to a system involving two stations. *ig. 2 is a diagrammatic view of a modified form of voltage regulator.

As preliminary to further description of my invention, it is advisable first to consider a generating and power transmitting system including. a General Electric Compan s voltage regulator, such as generally installed by that company and generally known as the and to which sys tem I have applied-my automatic controller, for the purpose of operating in multiple voltage regulators of two distant generating plants with the generators operating in multiple and delivering energy to the same power transmission line.

An earlytorm of the resent generally used or standard Tirrill voltage regulator is diswinding 3,

' voltage.

closed in Letters Patent No. 725,800, issued to A. A. Tirrill'oi date April 21, 1903, and entitled Automatic potential regulator.

The diagram view Fig.1 at the left, shows the elementary connections of a General Electrio voltage regulator, to two alternating generators and one excit'er, the generators shown being of the three phase type. consists of a relay ma net 1, a direct current control magnet 12, am an alternating current control magnet 3. T l". e A. C. magnet 3 has two The regulator.

windings 3 and 3 and a movable core 3.

The winding 3 is a potential Winding, which isconnected, asshown, by means of transformer 41 across the A. C. bus bars or. mains, of the power transmission line 5. crease of" potential will raise the core of this magnet 3, while a decrease of potential will low-or the same. The compensating winding 3* is connected, by means of the current transformer 6, to. one of the bus bars or mains, of the power transmission line 5. The current in this winding 3 flows in opposite direction to the current-in the otential and demagnetizes the atter in direct proportion to the current flowing, and in this way the generator or bus bar voltage is raised, to automatically compensate for line transformer and secondary losses. This compensating winding 3 can be adjusted for any line loss desired. However, with the compensating winding cut out the regulator will maintain a constant generator or bus bar The core 3 of the magnet 3 is connected to an intermediately pivoted lever 7 that carries the lower main contact 7 and is subject to a weight 7". The winding 2 of the magnet 2 is connected across the bus bars 8 of the exciter 8. The core of this magnet 2 is drawn downward by an increase of potential in the winding 2" and is released and allowed to raise on a decrease of potential in the winding 2 The'core of the magnet 2 is connected to an intermediatel-y pivoted lever 9 andcarries the upper main contact 9*, at one end,.directly overlying the contact 7, and at its other end said lever is yieldingly drawn u ward bya sprin 9 l The re ay magnet 1 18 di. erentially wound, having one winding 1 permanently connected to the exciter bus bars 8, andanother winding 1 onnected in the same manner, except that its circuit is opened and closed by the main contacts 7 and 9. The

, minimum load. To

The condenser 11" are inserted in the effect of the 1 is to demagnetize the winding 1, when' t e main contacts 7.9' are closed, thereby releasing the spring so ported relay armature 10 and causing t e same to close the relay contact 10". The relay contacts 10 open and close a shunt circuit 11, acrossv the exciter field rheostat' 1 11" serves 'to take up the arc,

acro'ssthe contacts 10, when the-shunt circuit is opened, by a separation of said conv field rhcostat 11* all in, as'shown. This regulator just described, acts only on the exciter field rheostat.- The alternating current generators 13 are connected to the bus bars or mains of the transmission line 5, through a group of transformers 14.

. We will suppose that the voltage regulator is in action, with rheostats adjusted as above stated, holding the bus bars, or generator voltage constant, and that a load is thrown on the alternating generators, which load would, of course, tend to lower the voltage. This, as is obvious, will weaken the 'A. C. control magnet 3, which would allow its core to be lowered. When the core of the magnet 3 lowers, it raises the main contact 7 into engagement with the main contact 9*,

which will, in turn, close the relay contacts 10, and short circuit the ciiciter field rheoa little; and at the instant it stat 11*. This will raise the exciter voltage,

almost instantly, until the generator voltage has been restored, and the core of the A. C. magnet 3 will cease its downward movement at this point. When this takes place, the lower-main contact 7 will have been raised ceases its upward movement, the D. C. control magnet 2 will continue to open and close the main contacts 7-9 very rapidly, and cause the relay contacts 10 to open and close simultaneously. The continued opening and closing of the rhcostat shunt circuit 11, by the re ay contacts 10, will cause, in rapid succession, slight weakening and strengthening of the D. C. control magnet 2, which will continue to 0 on and close the inain contacts 'Z9 ant relay contacts 10, and thereby maintain a new constant voltage on the exciter 8, until another disturbing factor has taken place on the generators.

The A. C. magnet contributes no movement to the opening and closing of the main and relay contacts, except that as the generator voltage tends to be varied from some cause, its core would take a lower position, if

the voltage of the generators tend to increase, and this, in turn, would lower the exciter voltage, because the D. C. magnet 2 would have to be weakened in order to open and close the contacts at the lowered position of the main contacts 79. These contacts, are, as is evident, of the class known as fioating contacts, and they usually raise about three thirty seconds of an inch in moving from "no-load to full-load position,- varying the exciter voltage from seventy to one hundred and thirty volts, in order to maintain the desired alternating voltage.

Considering now the action of the current winding 3 of the magnet 3, it should be first stated that the effect of this winding is simpl to demagnetize the potential winding 3". heweakening of the potential winding 3 bythe current winding 3", will her are .more or less in proportion to the cement flowing out on the mains 5. If the load becomes greater, the current in this winding 3 will be increased and will demagnetize the potential winding 3 to a greater extent, and thereby cause the exciter voltage to raise, and in this way to maintain a constant voltage at the center of distribution (which center of distribution may be several miles away), thereby overcoming line, transformer arid secondary line losses. In brief,

the regulator short-circuits the exciter field rhcostat, for a greater or shorter length of time, depending on the load and s eed, as required to maintain the desired vo tag-e at the center of distribution.

My present invention was primarily the result of the following conditions: A generating station at Apple River Falls, Wisconsin, known as the St. Croix station, transmits four thousand horse power of electrical energy to St. PauL-Minnesota, a distance of about't-wenty eight miles, and in this station, a General Electric ty c of voltage regulator, such as above doscri )ed, has been us regulate for voltage and to compeu: line losses, not only to Paul, hi it through to the consumer. The drop t lo-load to tull-load was apprcxin twenty three percent. and consequently, or bus bar voltage at the generating station had. to vary twenty two eroent, between zero and full-load. At liverdale, Wisconsin, about six miles from the St. CroiX station, another generating station having approxi-, mately the same kind of equipment as the St. CroiX station, but of much lesscapacity, the maximum output thereof being about one thousand horse power. It became desirable to connect the two stations in multiple, to-wit, the St.CroiX station having a caacity of four thousand horse power and the ivcrdale station having a capacity of one thousand horse power, to the same transmission line, to-wit, to the line, or mains, running into St. Paul. In order to have the volsenses tage regulator at the Riverdale station work at all, it had to compensate for from zero to twenty three percent. line drop, on a load varying from zero to one thousand horse power. Under these conditions, the two voltage regulators of the two distant enerating systems would operate in multiple when, and only when, each station carried the same ratio of its full load. For instance, if the St. Croix station carried fifty percent. of its full load,

which would be two thousand horse power, then Riverd ale would also have to carry fifty ercent. of its full load, which would be five undred horse power. But this is a condition which, in practice, can. not be maintained, and consequently, the voltae regulators would not work together, an Riverdale regulator had to be cut out. A man had to be employed to regulate the fields oi the generators, by adjusting the lield rheostats 12. My invention meets the above conditions and makes it possible to control generators in distant stations, according to voltage and power factor changes in the transmission line to which they areconnected.

I will now describe my invention as applied to. the two generating stations, each involving a voltage regulator, as above described, and illustrated diagrammatically in Fig. 1; and for convenience will refer to the two stations as the St. CIOiX station and the River regulator.

dale station. a In this diagram view Fig. l, the mains of the two stations are shown as connected at 15, so that both stations deliver to the main power transmission line .5. In my experiments up to the present time I have found that where two or more generating stations are run in parallel, the stations being. some distance apart, and the one station lar er than the ot er, as in the instance above illustrated, it is best to use the voltage regulator at the larger station, to-wit, the. St. Croix station, to regulate purely for voltage at the St. Paul end or delivery end of the power transmission line, and to keep the 'voltage constant at that point, no matter how much the load may vary; and to make the voltage regulator at the smaller or Riverdale station, follow up the changes in the bus bar voltage at the St; Croix station or main 'sta tion, so that the Riverdale regulator thereby becomes, to a certain extent, a power factor To do this, I connect a pressure circuit, to wit a pair oi pressure wires l6 at the St. Croix station, to a step-down potentialtranstormer 17, this transformer being, on the high tension side, connected to the high tension bus bars or mainsoi the St. Croix station. These pressure wires 16 are run to the Riverdale station. where they connect to the high tension side of a transformer 18 which, as shown, is a potential transformer. The low tension side {of this transformer 18 is connected to a coilor 'inding" 19 that surrounds the lower portion of the core 3 oi the A. C. control ma net 3 of the vol tage regulator at the River ale station. This coil 19 has the same number of ampere turns as the potential winding 3 of said magnet 3, and is set just'as far down and extends just as far below the lower part of said core, as the coil or winding 3 extends beyond thegupper part of said. core. The current in the coil 19 travels in opposite directionto the current in the coil; or winding 3, and hence, the two coils 19 and 3 pull upon the core 3 in opposite directions. At present we will not conider the action of the current or compensatin winding 3*. The potential winding 3 of this control magnet of the voltage, or field current regulator, at the Riverdale station is,

of course, connected to the mains or bus bars 13 of the generator at the Riverdale station, through the potential transformer "4. The coil 19 being connected to the pressure wire transformer fl8,'receives a voltage substantially equal to the bus bar voltage at the St. Croix station.

Operation: if the voltage in winding 3 equals the voltage i'nthe coil 19, the .core 3 will not move and the exciter voltage will not change. But sup ose an increasedload comes 7 upon the St. Croix or main station, the voltage regulator at that station raises the bus bar voltage, and this raises thevoltage in the pressure wires 16 and also in the coil 19, and thus causes the core 3-of"*the Riverdale voltage regulator to be lowered, and this, in turn, causes the exciter voltage to raise, and thereby the generator voltage, until a balance is reached between pressure wire coil or winding 19, and the generator potential coil 3 of the said Riverdale station. Now suppose some of the load drops chat the St. Croix station. This will cause the voltage regulatorat that station to lower the voltage of said station, and this will cause less voltage on pressure wires 16 and pressure wire coil 19. This will allow the coil 3 of the voltage regulator at the Riverdale station to pull upward the core 3 and thereby lower the exciter voltage and, consequently, the generator voltage, at the Riverdale station, until a balance has been reached. The current winding 3 of the magnet 3 of the regulator at the Riverdale low up and maintain the voltage of the gen- I erators of the St. Croix or main station, at the point of junction 15, of the transmission lines. Stated in another way, the two distant generating'stations are caused to main-- tain the same voltage at the points where their transmission lines are joined.

As further illustration of the action of the "automatic controller on the voltage regulaergizing thcicoil 19, with equal forces, but

acting on the core 3 in opposite directionsthe result is zero. Consider the generator voltage at the Riverdale station to increase and the pressure wire .voltage to remain constant, the result is no longer zero, and the core 3" is drawn upward thus (throu h the voltage regulator already described) owering the exciter voltage at the Riverdale station, and the exciter lowers the generator voltage, until it equals the pressure wire voltage. Consider the generator voltage at the lliverdale station as constant and the pressure wire voltage. to be raised, the result is not zero and the core 3 is drawn downward, thus causing the exciter voltage to raise; and

the exciter voltage then causes the generator voltage to ra se, until the two voltages are again equal. 'lhis Wlll mean that the main contacts 7"9 of the re later at Riverdale have raised a little and t at the exciter. and also the generator, are working with a higher voltage. The above conditions will be strictly correct both at the Riverdale station and at the junctions 15 of the transmission lines, provided no load was transmitted quer the power line from the Ptiverdale station to the said junction 15. But as current, and consequently load, is coming on, there is a percentage drop in the voltage between the Riverdale station and the said junction of the two lines; and this percentage ofdrop is substantially proportional to the current-flovw ing over the line and to the iase relation of rurrzjwnt and voltage. But trie current transi'ormer 6 at the Rivcrdale station has, in its secondary, a current in step with and alwavs in proportion to the current flowing inthe.

main or bus banin which it is inserted. This prop iional current flowing in the secondary of said current transformer, of course, also flows through the current winding 3 to which it is connected, and as this current flows through the said winding 3 in a direction opposite to the flow of the current from the potential transformer, in the potential winding 3*, it of course tends to demagnetize the said winding 3, in direct proportion'to the phase relation of the currents in the coils and the current flowing on the line. And this is sowhether the load be inductive or .non-inductive. In this way, the drop between the Riverdale station and the junction of the two lines at 15 is compensated for.

The ideal construction foran alternating current magnet to be used in a voltage regu- 'tial winding 3 and the current winding 3 are applied around the core 23, and the poten tial winding or coil 19 which is connected to the pressure wires 16 through the transformer 18, as already described, is ap lied around the core 3. To prevent trem lin f and sudden movements of the two cores an connections which receive movements therefrom, a piston 25 which works in a dash pot 26 is, as shown, attached to the core 3".

It will, of course, be understood that while my invention has been particularly described for use to automatically control the generators of stations that are a long distance apart, it is equally well adapted to control generators that are in close proximit to each other, but connected to deliver t on energy to the same transmission line. Hence,

it will be understood that the expression distant stations is used for the sake of convenience and is not intended as a limitation as to the distance between the several generators.

What; I claim is:

1. The combination with several alternating'electric power stations connectedlin parallel with the transmission line, each station including a voltage regulator, said voltage regulator at one station serving to determine the voltage on the main transmission line, and means for subjecting the voltage regulator at each other station or stations to the influence of the voltage of the transmission line at the point of junction of the line from the corresponding station with the transmission line.

2. The combination with main and supplemental alternating current generating stations, operating in synchronism and con nected in parallel to a common transmission line, with the main station regulated to determine the voltage at the distributing end of the line, of a device responsive to voltage variations at the junction of the lines from the main and supplemental stations, and operating to control the supplemental station to secure delivery therefrom to the main line at the same voltage as from the main station, substantially as described.

3. The combination with main and supplemental alternating current generating stations, operating in synchronism and connected in arallel to a common transmission line, with t e main stat-ion regulated to determine the voltage at the distributing end of the 1o 'enerating plants, each having a voltage e ulator and having generators'arranged to de 'ver their energ to the same transmission line, one of said l ant's serving to determine the voltage on tie transmission line, of inductive means for controlling the voltage regulators at the other plants in accordance with the voltage on the transmission line at the points of junction of the lines from the i orrespondin'g stations with the transmission 5. The combination with several alternatin current power stations connected in paral e1 with a transmission line, each station including a voltage re ulator and one station serving to determine t e voltage on the transmission line, of an induction circuit connected between the voltage regulator at each-of the other stations and the'junction of the corresponding station'line' with the transmission line to control the several voltage regulators in accordance with the voltage of the transmission line at the points of junction.

6. The combination with several electrical generating stations having their generators arranged to deliver their energy to the same transmission line, and each station including a voltage regulator, of a p ssure circuitre ceiving energy approximately at the point of junction of the station lines with the common transmission line, and a coil operative on the voltage regulator of'one of the stations and receiving ener y from the said pressure circuit, whereby said latter voltage regulator will be controlled according tothe voltage and power factor variations on the common transmission line. Y

7. The combination with several electrical generating stations having theirge'nerators.

' of a pressure circuit receiving energy approxlmately at the point of junction of the station lines with the common transmission line, and a coil receiving energy from said pressure circuit and acting in 0 position to one of the controlling coils of t e voltage regulator at one of the stations, whereby said latter vol-- tage regulator will be controlled according to the voltage and power factor variations on the common transmission line.

8. The combination with several electricai power stations delivering their energy to the said voltage regulators comprising a potential winding arranged to act on thefcircuit closing devices of one of said volta e regulators in opposition to the potentia windin thereof, and pressure'wires connected to sai potential winding by a potential transformer and connected to the common transmission line by a second potential transformer, substantially as described.

-9. The combination with several electric generators delivering their energy to a common transmission line, of a voltage regulator .for each generator, and a circuit receiving electric energy from the leading or main generator and influencing inductively the vol-' tage regulators of the other generators so as to cause the same to follow the main or lead ing generator in respect to voltage variation, whereby uniformvoltage will be delivered to the main line from all of said generators and cross currents between the several generators be prevented.

10. The combination with several electrical 5-K generating stations having their generators arranged to deliver their energy to the same transmission line, of a voltage regulator for each station, and a circuit receiving electric energy from the main station and influencing if inductively the voltage regulators of the other stations, so as to cause the subsidiary.

generating stations to follow the main or tion, whereby uniform voltage will e delivered to the main or transmission line from all leading station, in respect tovolta e varia- 

